The traditional business model for electrical test companies has been to periodically run tests on their clients’ electrical assets. This would provide a certain level of comfort to customers that their equipment was in good working order and would remain that way until the next scheduled test.
That isn’t always the case though — failures can occur in between tests. Given the high impact of failures, the aging of medium-voltage assets, and the growing number of options in cost-effective monitoring solutions, a change is taking place. End users are increasingly installing 24x7 monitoring on their medium- and high-voltage assets so that potential problems are spotted when they start and are more likely to be rectified before failure occurs.
Cost-effective monitoring systems and services for thermal increase and partial discharge (PD) are now readily available. Thermal monitoring checks the health of the conductors and can take the place of periodic infrared scans while reducing the need for visual inspections. PD monitoring checks the health of the insulation and can take the place of periodic PD surveys.
Test companies that rely on infrared and PD surveying of medium- and high-voltage equipment and do not adapt to this change may suffer in the coming years. An end user who buys a 24x7 monitoring system needs less periodic testing, thereby reducing the business available to test companies. Test companies that adapt and offer to install monitoring systems and manage them by responding to alerts could see their business increase. It is important for electrical test companies to understand this paradigm shift and plan accordingly in order to ensure the continued success of their businesses.
Periodic Testing
Periodic testing is certainly better than no testing, but it isn’t perfect. All it takes is for a problem to go from undetectable to failure in less time than the period between the surveys for potentially catastrophic losses to occur. As the frequency of testing increases, the chance of failure decreases, but, at some point, that becomes too labor intensive and financially onerous to support.
The obvious analogy is the increasing use of 24x7 wearable EKG monitors for heart patients. Getting an EKG done once a year during a physical is great, but serious issues can occur between visits. For most people, the inconvenience and cost of such a device makes it not worth the benefit, but as the cost goes down and convenience goes up, who knows? For high-risk patients, it can literally be a lifesaver.
Typically, on assets above 2.5 KV, PD testing is done annually or biannually because the general belief is that PD takes at least that long to lead to failure. That is sometimes, even often, true, but it is not always the case. Take the following incidents for example.
Example 1: U.K. Distribution Utility
In November 2014, this U.K. utility installed an ultrasonic and Transient Earth Voltage (TEV) monitor at one of its high-risk substations. The site was deemed high risk due to its location near a river’s edge combined with the type of switchgear operated at the location. Tragically, there was no remote communication channel available, and the system data was not being reviewed during the testing period. On July 28, 2015, the switchgear failed catastrophically (see Figure 1).